NASA’s TESS Discovers Three New Worlds

NASA’s Transiting Exoplanet Survey Satellite, otherwise known as TESS, has discovered three new planets in a solar system called The TOI 270 System.

TOI (TESS Object of Interest) 201 is located roughly seventy-three light-years away in Pictor, a constellation in the Southern Celestial Hemisphere. The three worlds orbit a M-type dwarf star that is about 40% smaller than the sun and burns faint and cool.

This infographic illustrates key features of the TOI 270 system, located about 73 light-years away in the southern constellation Pictor. The three known planets were discovered by NASA’s Transiting Exoplanet Survey Satellite through periodic dips in starlight caused by each orbiting world. Insets show information about the planets, including their relative sizes, and how they compare to Earth. Temperatures given for TOI 270’s planets are equilibrium temperatures, calculated without the warming effects of any possible atmospheres. Credit: NASA’s Goddard Space Flight Center/Scott Wiessinger

The closest planet to the star is named TOI 270 b or planet B for short, appears to be of rocky composition and is almost 25% larger than Earth, with a mass 1.9 times greater than Earth. It orbits the star every 3.4 days at a distance about 13 times closer than Mercury is to the Sun. Due to this close proximity, it is estimated that the temperature on the surface would be 490 degrees Fahrenheit (254 degrees Celsius).

The other two planets, TOI 270 c and TOI 270 d (planets C and D), are both over two times larger than Earth and are thought to be mainly composed of gas rather than rock. Some of their characteristics most closely resemble our Neptune, but smaller. TOI 270 c orbits its star every 5.7 and has a mass seven times that of Earth’s. TOI 270 d takes 11.4 days to get around the star, with a mass five times greater than Earth’s.

All three planets are thought to be tidally locked meaning that they only rotate once every orbit and keep the same side facing the star at all times. Our Moon is also tidally locked, causing Earth to only ever see one side.

GIF version. Compare and contrast worlds in the TOI 270 system with these illustrations of each planet. Temperatures given for TOI 270 planets are equilibrium temperatures, calculated without taking into account the warming effects of any possible atmospheres. Credit: NASA’s Goddard Space Flight Center

A paper on TESS’s findings has been published in the journal, Nature Astronomy.

Maximilian Günther, lead researcher and a Torres Postdoctoral Fellow at the MIT Kavli Institute for Astrophysics and Space Research in Cambridge, explains why this is exciting, “This system is exactly what TESS was designed to find — small, temperate planets that pass, or transit, in front of an inactive host star, one lacking excessive stellar activity, such as flares,”. “This star is quiet and very close to us, and therefore much brighter than the host stars of comparable systems. With extended follow-up observations, we’ll soon be able to determine the make-up of these worlds, establish if atmospheres are present and what gases they contain, and more.”

Co-author of a paper describing TESS’s findings recently published in Nature Astronomy, Fran Pozuelos, says, “An interesting aspect of this system is that its planets straddle a well-established gap in known planetary sizes. It is uncommon for planets to have sizes between 1.5 and two times that of Earth for reasons likely related to the way planets form, but this is still a highly controversial topic. TOI 270 is an excellent laboratory for studying the margins of this gap and will help us better understand how planetary systems form and evolve.”

Although the first three planets are not considered suitable for a habitable world, scientists are hopeful further studies of this solar system will reveal additional rocky planets further enough away from its star therefore cool enough to contain liquid water